Patent application title: LED ILLUMINATION APPARATUS

Abstract:

The present invention aims to realize a technique to make precise
chromaticity changes over a wide range in an LED illumination apparatus
based on a white LED light, and comprises a first LED; a package for
accommodating said first LED; a transparent medium for filling said
package, said transparent medium containing a fluorophore which generates
a white light when said first LED emits light; and a plurality of LEDs,
wherein said first LED and the plurality of LEDs respectively have
different dominant wavelengths.

Claims:

1 An LED illumination apparatus, comprising:a first LED;a package for
accommodating said first LED;a transparent medium for filling said
package, said transparent medium containing a fluorophore which generates
a white light when said first LED emits light; anda plurality of LEDs,
whereinsaid first LED and the plurality of LEDs respectively have
different dominant wavelengths.

2. An LED illumination apparatus, comprising:a first LED;a package for
accommodating said first LED;a transparent medium for filling said
package;another transparent medium for covering said transparent medium,
said another transparent medium containing a fluorophore which generates
a white light when said first LED emits light; anda plurality of LEDs,
whereinsaid first LED and the plurality of LEDs respectively have
different dominant wavelengths.

3. The LED illumination apparatus according to claim 1, whereinsaid
plurality of LEDs are accommodated in said package with said first LED.

4. The LED illumination apparatus according to claim 2, whereinsaid
plurality of LEDs are accommodated in said package with said first LED.

5. The LED illumination apparatus according to claim 1, whereinsaid first
LED generates a blue light.

6. The LED illumination apparatus according to claim 2, whereinsaid first
LED generates a blue light.

7. The LED illumination apparatus according to claim 3, whereinsaid first
LED generates a blue light.

8. The LED illumination apparatus according to claim 1, whereinsaid first
LED generates an ultraviolet light.

9. The LED illumination apparatus according to claim 2, whereinsaid first
LED generates an ultraviolet light.

Description:

[0001]This application is based upon and claims the benefit of priority
from Japanese patent application No. 2008-016356, filed on Jan. 28, 2008,
the disclosure of which is incorporated herein in its entirety by
reference.

[0005]An illumination apparatus utilizing an LED is disclosed in Japanese
Patent Laid-Open No. 2004-80046.

[0006]Japanese Patent Laid-Open No. 2004-80046 describes that when a white
light emission is obtained by combining a red, green, and blue LED
element, color irregularities are likely to occur and when a white light
emission is obtained by combining a blue LED element and a yellow
fluorescent substance, poor reproducibility of red color results; and
discloses a technique to achieve an LED illumination apparatus having a
good color rendering property by supplementing a red color component,
which lacks a white LED, through combining white and red LEDs.

[0007]Currently, fluorescent lights are used for the illumination of
showcases and the like. When an object to be illuminated is known, the
requirement is for a particular illumination that enables a desired color
to stand out. For example, in the case of a showcase for meat products,
illumination by a light source having a red-rich spectrum will make the
meat products look fresher, and in the case of a showcase for vegetables,
an illumination by a light source having a green-rich spectrum will make
the vegetables look fresher. However, it is often the case that the
desired light color subtly varies depending on the difference in the
interior illumination of stores and people's tastes.

[0008]Currently, the sale and developments of LED illumination apparatuses
for showcases is conducted in such a way that fluorescent light samples
are brought to the customer's premises and the samples are made to emit
light on-site to observe the customer's response.

[0009]Such method may require a significant amount of time and cost
because, if the light emission characteristics of the sample that has
been brought to the customer do not satisfy the customer's need, it is
necessary to create samples having new light emission characteristics and
to bring them to the customer again.

[0010]In the technique disclosed by Japanese Patent Laid-Open No.
2004-80046, a red color component which lacks a white LED is supplemented
by combining a white LED and a red LED; however, precise control of the
light color over a wider range will be difficult since the intensity is
to be controlled by a single red LED.

[0011]When illuminating a particular object, such as object displayed in a
showcase, what is desired is that a particular color be made to stand out
in order to enhance the appearance of the particular object. In order to
achieve that, it is necessary to make precise chromaticity changes over a
wide range in a particular region.

SUMMARY OF THE INVENTION

[0012]The present invention aims to realize a technique to make precise
chromaticity changes over a wide range in an LED illumination apparatus
based on a white LED light

[0013]The LED illumination apparatus according to the present invention
comprises:

[0014]a first LED;

[0015]a package for accommodating said first LED;

[0016]a transparent medium for filling said package, said transparent
medium containing a fluorophore which generates a white light when said
first LED emits light; and

[0017]a plurality of LEDs, wherein

[0018]said first LED and the plurality of LEDs respectively have different
dominant wavelengths.

[0019]The LED illumination apparatus according to another aspect of the
present invention comprises:

[0020]a first LED;

[0021]a package for accommodating said first LED;

[0022]a transparent medium for filling said package;

[0023]another transparent medium for covering said transparent medium,
said another transparent medium containing a fluorophore which generates
a white light when said first LED emits light; and

[0024]a plurality of LEDs, wherein

[0025]said first LED and the plurality of LEDs respectively have different
dominant wavelengths.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a sectional view to show the configuration of an exemplary
embodiment of the LED illumination apparatus according to the present
invention;

[0027]FIG. 2 is a top view to show the layout condition of each LED of the
exemplary embodiment shown in FIG. 1;

[0028]FIG. 3 shows a spectral distribution of the LED illumination
apparatus when each LED of the exemplary embodiment shown in FIG. 1 is
caused to emit light individually;

[0029]FIG. 4 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 1;

[0030]FIG. 5 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 4;

[0031]FIG. 6 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 1;

[0032]FIG. 7 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 6;

[0033]FIG. 8 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 1;

[0034]FIG. 9 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 8;

[0035]FIG. 10 is a sectional view to show the configuration of a second
exemplary embodiment of the LED illumination apparatus according to the
present invention;

[0036]FIG. 11 is a top view to show the layout condition of each LED of
the exemplary embodiment shown in FIG. 10;

[0037]FIG. 12 shows a spectral distribution of the LED illumination
apparatus when each LED of the exemplary embodiment shown in FIG. 1 0 is
caused to emit light individually;

[0038]FIG. 13 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 10;

[0039]FIG. 14 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 13;

[0040]FIG. 15 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 10;

[0041]FIG. 16 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 15;

[0042]FIG. 17 shows a light emitting state of each LED of the exemplary
embodiment shown in FIG. 10;

[0043]FIG. 18 shows the spectral distribution of the LED illumination
apparatus in the light emitting state shown in FIG. 17; and

[0044]FIG. 19 is a sectional view to show the configuration of another
exemplary embodiment of the LED illumination apparatus according to the
present invention.

EXEMPLARY EMBODIMENT

[0045]Next, exemplary embodiments will be described with reference to the
drawings.

[0046]FIG. 1 is a sectional view showing the configuration of an exemplary
embodiment of the LED illumination apparatus according to the present
invention.

[0047]There are disposed blue LED 1, red LED 2, and red LED 3 in the
bottom face of package 4 made of plastics ceramics, and the like, and
fluorophore-containing transparent medium 5 into which a fluorophore is
mixed is packed on top of the each LED.

[0048]FIG. 2 is a top view showing the layout condition of each LED, in
which red LED 2 and red LED 3 are disposed in symmetry with respect to
blue LED 1 interposed therebetween.

[0049]FIG. 3 shows a spectral distribution of the LED illumination
apparatus when each LED is caused to emit light individually.

[0050]10 As shown in FIG. 3, each LED has a different dominant wavelength.
Further, a fluorescent light is generated through a light emission of
blue LED 1 and also a green light and a red light are generated when blue
LED 1 emits light so that a white color is observed as a whole. It is
noted that the blue LED may be an LED which generates an ultraviolet
light.

[0051]The LED illumination apparatus of the present exemplary embodiment,
in which the main illumination source is blue LED 1, uses an LED which
has the largest output power among the LEDs as blue LED 1, and which
exploits the light emission of red LED 2 and red LED 3 to control the
light color. A drive circuit (not shown) for each LED is separated
respectively and is configured such that each light emission can be
controlled individually. Blue LED 1 and red LEDs 2 and 3 may be packaged
separately.

[0052]When blue LED 1 and red LED 3 are caused to emit light as shown in
FIG. 4, the spectral distribution shown in FIG. 5 will result. When blue
LED 1 and red LED 2 are caused to emit light as shown in FIG. 6, the
spectral distribution shown in FIG. 7 will result. When blue LED 1 and
red LEDs 2 and 3 are caused to emit light as shown in FIG. 8, the
spectral distribution shown in FIG. 9 will result.

[0053]Next, a second exemplary embodiment will be described with reference
to the drawings.

[0054]FIG. 10 is a sectional view showing the configuration of a second
exemplary embodiment of the LED illumination apparatus according to the
present invention.

[0055]There are disposed blue LED 11, green LED 12, and green LED 13 in
the bottom face of package 14 made of plastics, ceramics, and the like,
and fluorophore-containing transparent medium 15 into which a fluorophore
is mixed is packed on top of the each LED.

[0056]FIG. 11 is a top view showing the layout condition of each LED in
which green LED 12 and green LED 13 are disposed in symmetry with respect
to blue LED 11 interposed therebetween.

[0057]FIG. 12 shows the spectral distribution of the LED illumination
apparatus when each LED is caused to emit light individually.

[0058]As shown in FIG. 12, each LED is configured to have a different
dominant wavelength. Further, a fluorescent light is generated through
the light emission of blue LED 11 and also a green light and a red light
are generated when blue LED 11 emits light so that a white color is
observed as pure white. It is noted that the blue LED may be an LED which
generates an ultraviolet light.

[0059]The LED illumination apparatus of the present exemplary embodiment,
in which the main illumination source is blue LED 11, uses an LED which
has the largest output power among the LEDs as blue LED 11, and which
exploits the light emission of green LED 12 and green LED 13 to control
the light color, A drive circuit (not shown) for each LED is separated
respectively and is configured such that each light emission can be
controlled individually. Blue LED 11 and green LEDs 12 and 13 may be
packaged separately.

[0060]When blue LED 11 and green LED 13 are caused to emit light as shown
in FIG. 13, the spectral distribution shown in FIG. 14 will result. When
blue LED 11 and green LED 12 are caused to emit light as shown in FIG.
15, the spectral distribution shown in FIG. 1 6 will result. When blue
LED 11 and green LEDs 12 and 13 are caused to emit light as shown in FIG.
17, the spectral distribution shown in FIG. 18 will result.

[0061]It is noted that although the exemplary embodiments have a structure
in which the entire package is sealed with a transparent medium into
which a fluorophore is mixed, a structure in which an LED sealing part
and a fluorophore containing part are separated as shown in FIG. 19 may
be used.

[0062]In an exemplary embodiment shown in FIG. 19, there are disposed blue
LED 101, red LED 102, and red LED 103 in the bottom face of package 104
made of plastics, ceramics, and the like; transparent medium 106 is
packed on top of the each LED; and fluorophore-containing transparent
medium 105, into which a fluorophore is mixed, is placed in such a way as
to cover transparent medium 106.

[0063]Further, when an ultraviolet LED is used as the excitation light,
mounting a plurality of blue LEDs each of which has a different dominant
wavelength will make it possible to perform precise chromaticity control
even in a blue region and therefore such a configuration may also be
adopted.

[0064]In the present invention configured as described above, a white
light is obtained by a first LED and a fluorophore-containing transparent
medium, and further a plurality of LEDs, each of which has a different
dominant wavelength, are provided. By differentiating the ON state of
each of the LEDs, it becomes possible to obtain lights with various
spectral distributions and to change the light color of one LED
illumination apparatus over a wide range by making precise chromaticity
changes. Since such an LED illumination apparatus has a higher potential
for realizing a light emitting characteristic which meets the customer's
need, it becomes possible to let customers choose their favorite colors
and to perform illumination design based on the data thus leading to a
reduction in time and cost.

[0065]While the invention has been particularly shown and described with
reference to exemplary embodiments thereof, the invention is not limited
to these embodiments. It will be understood by those of ordinary skill in
the art that various changes in form and details may be made therein
without departing from the spirit and scope of the present invention as
defined by the is claims.